Immersion heater



Aug, 3, 1937. H. w. COLE ET AL IMMERS I ON HEATER INVENTOR W ('0 le Filed June 29, 1955 Harry Bgeorge M.Ma.rr

ATTORNEYS Patented Aug. 3, 1937 UNITED STATES PATENT OFFICE Marr, Woodhaven, N.

ditioners, Inc., New tion of Delaware Application June 29,

2 Claims.

Heaters of the type specified usually consist of closed casings or tubes in which the heaters are mounted, the heater units being insulated from the casing. When such heater units are heated to high temperatures any air trapped in the casing will be expanded and tends to puncture the seal and cause leakage into the casing.

This invention has for its salient object to pro vide an immersion heater of the character described so constructed and arranged that it will be tightly sealed and will not leak after it has been heated to high temperatures.

Another object of the invention is to provide a heater of the character described with contact terminals or members so mounted in the contact block as to prevent current leakage between the contact members or terminals and between said members and heater casing.

Another object of the invention is to provide a heater of the character described that is rugged in construction and will not be damaged or broken by rough usage.

Further objects of the invention will appearfrom the following specification taken in connection with the drawing which forms a part of this application, and in which Fig. 1 is a longitudinal sectional elevation of the heater constructed in accordance with the invention;

tact terminals and block in which they are mounted; and

Fig. 3 is an end elevation of the casing with the terminals extending therethrough'prior to the securing of the contact block in position.

The invention briefly described consists of an immersion heater comprising a casing having a heater unit mounted therein between closed ends of the casing, contact members projecting through one end and secured to a contact block. The heater units are secured to a block adapted to fit within one end of the casing and the block and terminals are secured to the closure for said casing end. After these parts have been secured in position the space between the heater unit and This is particularly dan- Fig. 2 is an enlarged end elevation of the con- Y., assignors to Air Con- York, N. Y., a corpora- 1935, Serial No. 29,050

the casing wall is filled with suitable insulating material, such as dry cement, this material being tamped in to tightly surround the heater unit and fill the space between the unit and the casing. The casing is then heated by an external application of heat and this causes any air in the casing to expand. When the casingv is heated to a high temperature the open end thereof is sealed and after the casing cools a partial vacuum will be formed therein. Thereafter, when the heating unit is heated by an electric current no expansion of air in the casing will take place and therefore the seals at the end of the casing will not be punctured.

Further details of the invention will appear from the following description.

In the particular embodiment of the invention illustrated, the immersion heater comprises a casing H) which consists of a metallic tube, one end of the casing being flared, as shown at H. To the flared end II is secured, in any suitable manner, as by brazing, a disc or closure I2.

The heater unit may be of any suitable construction and preferably comprises a core [5 of suitable insulating material, the core preferably being formed in sections which are mounted on the centrally disposed rod IS. The rod I6 is secured to a block I! of suitable insulating material, such as lava, and a nut l8 at the other end of the rod secures the core sections thereon.

The core l5 has formed therein spiral grooves I9 in which is mounted the heating wire 20, one end of the wire being shown at 2| and the other end being shown at 22. The wire is looped, as shown at 23, around a lug 24 disposed adjacent the end of the core IS.

The end 2| of the heater wire 20 is connected to a contact member or terminal 25 and the end 22 is connected to a similar terminal 26. These terminals consist of screws which are countersunk, as shown at 21, in the block l1. On each screw is mounted a nut 28 which is also countersunk in the block IT, as shown in Fig. 1, and secures the screw to the block. A brass washer 30 is disposed above or outside the nut 28 and a mica washer -3l is disposed above the washer 30 and beneath the closure or disc l2. An insulating washer 32, preferably of mica, is disposed above the washer 30 and insulates the terminal 50 member or screw 25 or 26 from the disc l2, the washer 30 spacing the screw from the opening 33 in the disc l2. Above the disc l2 or outside 5 thereof is disposed a washer 35 of mica or suitable insulating material and a brass washer 35 is dis- 55 posed outside the washer 35. A nut 31 engages the outer surface of the washer 36.

In the foregoing manner the terminal members or screws 25 and 2,6 are firmly secured to the block l1 and disc or closure l2 and are effectively insulated from the closure.

On the outside of the closure I2 is mounted a terminal block 40 formed of suitable insulating material and having countersunk openings 4! in the bottom thereof which receive the washers and nuts Just described. The screws 25 and 26 extend outwardly through openings 42 and 43, the

outer ends of the screws being disposed in pockets or recesses 44 and 45 which are separated by a central wall 45. The block is secured in position by nuts 41 and 48 which are mounted oh the screws and washers 49 and 50 are disposed between the nuts in the block. In addition to being secured by the nuts the block is preferably cemented to the closure I2. I

The block 40 is recessed in the manner described to form the pockets 44 and 45 in order to prevent current leakage between the terminals 25 and 25 and also between these terminals and the casing l0. It will be obvious that the length of the paths between these parts is sufiicient to prevent such leakage.

After the closure l2, block I I and terminals 25 and 28 have been secured and sealed to the flared end of the casing III, the space between the heating unit and the casing wall is filled with suitable insulating material, such as dry cement 55, which is tamped in to tightly fill this space. Heat is then applied to the outer surface of the casing ID in any suitable manner, as by a blow torch and this will cause any air in the casing to expand. While the casing is still heated to a high temperature the outer end thereof is sealed by a closure 58 which is brazed in the end of the-casing, as shown at 51; After the cement 55 has been tamped in and before the closure is secured in position a washer 58 may be inserted, as shown in Fig. 1, this washer being formed of insulating material, such as mica. packing of insulating material may then be tamped in outside at the washer before the closure 50 is secured.

A further 5 When the heater is constructed in the manner just described there will be a partial vacuum therein since the air was expanded by heat and the end of the casing was sealed when hot. As the heater cooled the contraction of the air formed the partial vacuum. Since this condition exists within the casing it will be obvious that the heating unit can be heated to a high temperature, but will not cause any expansion of air within the casing or puncture the seal.

It will be obvious from the foregoing description that the immersion heater constructed as described will be rugged in construction and that no leakage will take place.

Although one specific embodiment of the invention has been particularly shown and described, it will be understood that the invention is capable of modification and that changes in the construction and in the arrangement of the various coopcrating parts may be made without departing from the spirit or scope of the invention, as expressed in the following claims.

What we claim is:

1. An immersion heater of the character described comprising a casing, an electric heating element in the casing, a terminal block sealed to one end of the casing, contact terminals carried by said block and extending therethrough and connected to the ends of the heating element, and dry insulating packing surrounding the heating element and insulating said element from the casing, a partial vacuum existing in said casing.

2. An enclosed heater comprising a tubular casing, a closure for each end thereof, sealed thereto, an insulating block disposed within the casing and secured to one closure, a heater unit connected to said block and extending longitudinally in the casing, contact members connected to said unit and extending through and insulated from the closure, said members being sealed to said closure, and closely packed insulating material in the casing enclosing and surrounding the heater unit, said casing having a partial vacuum therein.

HARRY W. COLE. GEORGE M, MARR. 

